1. Digestion Continued Pancreas and Liver Respiration
Histology 14
Digestion Continued
Pancreas and Liver
Respiration

2. Announcements
Strike
Extra Credit
Research

3. Large Intestine (generic)
Principal functions:
Recovery of HOH and salts from feces
Propulsion of feces into rectum
Also divided into three parts. Its total length is approx. 1.5 m long but it has a greater diameter than the small intestine.
No villi
Intestinal glands – mucus
Crypts of Lieberkühn
Surface epithelia – mostly goblet cells and absorptive cells
Specialized muscularis externa
Longitudinal muscle is separated into three independent bands

4. Anatomical Divisions of L. Intestine
Caecum:
It is the blind end of the large intestine. Attached to it is the appendix. It is thought to play a role in fighting infection.
Colon:
Undigested food enters the colon and water and minerals are absorbed
Intestinal bacteria help break down some of the undigested food so it can be absorbed.
These bacteria also produce vitamin B12 and K as well as some amino acids
Rectum and Anal Canal:
Waste material (feces) moves into this region and is expelled through the anus.

5. Large Intestine

6. Long section of the colon (4x)

7. Long section of colon (100x)
2 main cell types:
1. goblet cells
2. absorptive cells

9. Sulculation caused by taeniae coli down to the anus – then continuous sheet of longitudinal muscle.

10. “End”notes Rectum – end of large intestine
Continuous sheet of long muscle
Anus – switches back to strat squam.
Goblet cells increase on way down.

11. Recto-anal junction

12. Section Epithelium Cell types in E. Other features
Esophagus
Stratified squamous
Squamous
Submucosal glands
Gradation of muscle
Body / fundus
Glandular – straight tubular
Surface mucous cells
Neck mucous cells Parietal cells
Chief (peptic) cells
Lymphoid sparse no aggregates
Pylorus
Glandular – coiled, branched tubular
Mucous cells
Occasional parietal
Duodenum
Glandular with villi and crypts of Lieberkühn
Enterocytes with microvilli
Goblet Cells
Paneth Cells
Brunner’s Glands
Jejunum / ileum
Peyer’s patches
Colon / rectum
Glandular – straight
Goblet cells
Absorptive cells
Teniae coli
Appendix
Glandular – straight crypts
Tall columnar cells
Prominent lymphoid aggregates
Anus
Absorptive and goblet
Squamous cells
Colums of Morgagni
Paneth Cells – lysozyme cells in bottom of crypts of lieberkuhn
Colums of Morgagni – longitudinal folds in colon (non-distended)
Peyer’s patches – lymphoid aggregates in colon
Brunner’s glands – another name for the glands at the bottom of the crypts of Leiberkuhn in the duodenum
Enterocytes – cells of epithelium

13. Pancreas and Liver Developmentally
Glandular outgrowth of primitive gut

14. Few notes on the Pancreas
In curve of duodenum
Lobulated Gland separated by septa
Exocrine Component – digestive enzymes from acini
can’t secrete active form
digest the gut
secretes proenzyme form (inactive enzyme)
Enterokinase (duodenal secretion) – activates proenzyme
Endocrine Component – Hormones – sugar metabolism
Insulin and Glucagon – decrease and increase blood sugar levels
Islets of Langerhanz
secreted into bloodstream
lots of capillaries associated with islets

15. Central lumen
Intercalated duct
Intralobular ducts
Interlobular ducts
Pancreatic duct
Ampulla of Vater
Duodenum

16. Pancreas (45x)

18. Exocrine Acinus (8500x)

19. Liver
Major functions
Detoxification of metabolic waste (deamination of amino acids – urea), drugs, toxins, alcohols
Destruction of spent RBCs and reclamation of their constituents (spleen does this too)
Synthesis and secretion of bile (consists of above)
Synthesis of lipoproteins, plasma proteins (including albumin and clotting factors)
Synthesis and storage of glycogen

20. Liver Largest gland in body (1500g)
Divided into 4 lobes (R, L, quadrate and caudate)
Endocrine and Exocrine components
Both are roles of the hepatocytes (liver cells)
Exocrine – bile
Endocrine – lots of stuff – added to sinusoids of hepatic lobules
Plus, noxious conversions added to bile
Intraperotineal

22. Pig liver (20X) C

23. Human (20X)

25. PV – portal venule A – hepatic artery L – lymphatic duct B – bile duct
S – sinusoids
Limiting plate
Limiting plate – specialized hepatocytes surrounding the portal tract (triad)

26. Respiratory System Main functions: Conducts air in/out
Exchange gasses w/blood – respiration
Includes mechanisms to prevent collapse of conducting tubes
Bones
Cartilage
Two major tube types:
Conducting pathway (nasal portion – lungs)
Respiration pathway (area of alveolar sacs)

27. Conducting Pathway Specialized lining of epithelium
“respiratory” epithelium that changes with arborization
Pseudostratified ciliated columnar epithelium
With goblet cells – secrete lots of mucus
Cilia beat in one direction:
Above pharynx – beat downwards
Below pharynx – beat upwards
Mucocilary
escalator
Mucus moved throughout passageway – trap dust

28. Conducting Pathway (cont.)
Blood vessels – warm and moisten air
Trachea (main passageway):
Contains C-shaped rings in adventitia
R,L primary bronchi (enter lungs)
Same as trachea
Cartilage becomes reduced in bronchi of lungs
Epithelium – begin with pseudostrat ciliated to ciliated columnar
Bronchioles
Epithelium – ciliated cuboidal to non-ciliated simple squamous
Terminal bronchioles
Respiratory bronchioles – start of the respiratory pathway
Decrease in cartilage, glands, goblet cells height of epithelium
Increase in smooth muscle and elastic tissue
Extrapulmonary-
Intrapulmonary-

31. Drawings of gas exchange

32. Trachea xs

33. Trachea ls E – epithelium LP – lamina propria SM – submucosa
F – fibroelastic tissue

34. Primary bronchus E – epithelium LP – lamina propria M – smooth muscle
G – seromucous glands
C – cartilage
Goblet Cells in epith.

35. Bronchiole
V – vein
M – sm. Muscle

36. Terminal portion of respiratory tree
T – terminal bronchiole
R – respiratory bronchiole
V – pulmonary vessel
AD – alveolar duct
AS – alveolar sac
A - alveolus